A known gas pressure regulator, diaphragm subassembly therefor and method of making same are disclosed in commonly owned U.S. Pat. No. 5,458,001 to Ollivier. A sequence of operations which has been employed in the past to form the diaphragm subassembly for the regulator includes mounting the components of the diaphragm subassembly in a diaphragm alignment fixture where the components are aligned, and then biasing the diaphragm a predetermined amount in the direction of the valve seat and compression member and thereafter further threading the valve or poppet of the diaphragm subassembly into the welded diaphragm plate of the subassembly so it comes into contact with the valve seat thereof. This condition is determined by observing a deflection of 0.001 inch of the diaphragm plate along the longitudinal axis of the valve using a suitable indicator during turning of the valve and its valve stem relative to the diaphragm plate as discussed in U.S. Pat. No. 5,458,001. This sets the biased position of the valve relative to the diaphragm plate. Thereafter, the diaphragm subassembly is removed from the diaphragm alignment fixture and inserted into a three jaw chuck crimper wherein an upper portion of the extension of the diaphragm plate receiving the valve stem is crimped to fix the relative position of the valve and diaphragm plate. The crimped diaphragm subassembly is then removed from the crimper and remounted on the diaphragm alignment fixture where a reverse torque test is performed on the crimped subassembly to determine whether the valve stem is properly crimped within the extension of the diaphragm plate.
This known sequence of operations and the related apparatus for performing them have been found to be disadvantageous in that they do not absolutely guard against accidental omission of the crimping operation during the manufacture of the diaphragm subassembly and the subsequent use of a biased, uncrimped diaphragm assembly in a regulator which can lead to failure of the regulator. They also require considerable handling of the parts of the subassembly with the attendant possibility for handling damage thereto. Further, the known method and apparatus require considerable assembly time and, because of the several handlings of the components, the opportunity for undesirable particle generation in a cleanroom application is increased.
The amount of crimp made by the three jaw chuck crimper is also imprecise which increases the scrap rate during manufacture. This problem is aggravated by problems in alignment of the biased subassembly with respect to the three jaw chuck crimper which can occur when the biased subassembly is mounted in the crimper for crimping.
An object of the present invention as to provide an improved method and apparatus for forming a diaphragm subassembly for a gas pressure regulator which avoid the aforementioned drawbacks and limitations of this known method and apparatus. More particularly, an object of the invention is to provide an improved method and apparatus for forming a crimped connection between parts of a diaphragm subassembly which prohibit the regulator failure mode caused by an operator's forgetting to crimp the subassembly during its manufacture, and which minimize parts handling and assembly time and also particle generation for cleanroom application while enabling fine control of the intensity of the crimp to permit rework on the diaphragm assembly, if necessary.
These and other objects are attained by the integrated crimp bias apparatus and the related method of the invention for forming a diaphragm subassembly for a gas pressure regulator wherein the apparatus comprises a fixture for holding components of the diaphragm subassembly to be biased relative to one another and connected together by a crimped connection between components thereof, means for biasing the components relative to one another, a crimper for engaging and deforming one of the components into another for forming the crimped connection, and a locking mechanism responsive to the presence of at least one of the components in the fixture to prevent removal thereof from the fixture before the crimped connection has been made. In this way, a predominant failure mode is prohibited by ensuring that each biased subassembly is crimped. Parts handling is minimized and assembly time reduced by aligning, biasing and crimping the subassembly in a single apparatus. Particle generation is also minimal for cleanroom application.
The fixture of the apparatus of the disclosed embodiment supports the diaphragm subassembly components including an annular, flexible metal diaphragm with a diaphragm plate secured to a central portion of the flexible metal diaphragm, a compression member, a valve seat supported by the compression member, and a valve for opening and closing a gas passage through the valve seat. The valve has a valve stem which extends through a gas passage of the valve seat and into an extension of the diaphragm plate which is adapted to be crimped to fix the relative positions of the valve and diaphragm plate in the subassembly after the flexible metal diaphragm is biased from an initial neutral position toward the compression member and valve seat by the means for biasing and the valve is set in contact with the valve seat.
The apparatus of the disclosed embodiment also further comprises means responsive to the operation of the crimper in forming the crimped connection for unlocking the locking mechanism to permit removal of the components from the fixture after forming the crimped connection. This unlocking preferably occurs after a short time delay such as 20 seconds, to permit reverse torque testing of the crimped connection before withdrawal of the subassembly from the fixture.
According to another feature of the invention, the crimper of the apparatus is a pincerlike crimper which includes a pair of pincers each having a handle to which a force can be applied and a grasping jaw for exerting a crimping pressure on the components to be crimp connected working on a pivot. The grasping jaws include a plurality of crimping elements in the form of pins carried by the grasping jaws for engaging and deforming a tubular member of the subassembly into the valve stem within the tubular member. The crimped connection is made by the application of a force at the handles turning the pincers at the pivot for exerting crimping pressure on the tubular member. In the disclosed embodiment, two crimping pins are carried by each of the grasping jaws. The pins oppose one another on opposite sides of the tubular member during crimping. Means are preferably provided for adjusting the relative position of the crimping pins with respect to their grasping jaws to obtain uniform crimping and adjust for wear of the pins.
These features of the invention advantageously permit the intensity of the crimp to be finely adjusted for obtaining a predetermined crimp without excessive deformation of the tubular member. Therefore, it is possible to rework components of a diaphragm assembly thereby reducing scrap during manufacture. The apparatus and method of the invention for forming a crimped connection between a first, tubular member and a second member extending within the first member also have applicability for connecting components other than those of a diaphragm subassembly for a gas pressure regulator.
A method of the invention for forming a crimped connection between a first, tubular member and a second member extending within the first member comprises holding at least one of the members to be crimp connected in a fixture which prevents at least the one member from being removed from the fixture before a crimped connection between the members has been made by a crimper, forming a crimped connection between the members with a crimper and removing the crimp connected members from the fixture. In the disclosed embodiment for forming a diaphragm subassembly, the diaphragm subassembly is aligned and biased in the fixture and thereafter the fixture and biased subassembly are moved together, without removing the subassembly from the fixture, into a position for performing the crimping with the crimper. After crimping, the fixture with crimped subassembly is returned to its initial position and the subassembly is reverse torque tested and then removed from the fixture of the apparatus for assembly into a gas pressure regulator.
These and other objects, features and advantages of the apparatus and method of the present invention will become more apparent from the following detailed description of a disclosed embodiment of the invention as illustrated in the accompanying drawings.